Heating tube for deep fat fryers



W. C. PROEH L Oct. 20, 1953 HEATING TUBE FOR DEEP FAT FRYERS 2 Sheets-Sheet 1 Filed June 7 1950 a t/ m a ZZ2Z W. C. PROEHL Oct. 20, 1953 HEATING TUBE FOR DEEP FAT FRYERS 2 Sheets-Sheet 2 Filed June '7, 1950 Z. BY I Patented Oct. 20, 1953 UNITED STATES OFFICE HEATING TUBE FOR DEEP FAT FRYERS William C. Proehl, Chicago, Ill.

Application June 7, 1950, Serial No. 166,663

7 Claims.

The present invention relates to improved heating tubes for deep fat fryers and the like.

In preparing various kinds of fried foods, such as French fried potatoes, chicken, shrimp, doughnuts, etc., it has become the regular practice in restaurants and hotel kitchens to employ relatively large containers capable of holding considerable quantities of a melted fat or of an oil which is kept heated to frying temperatures, around 400-43Q F.

In order to avoid too great chilling of the heated fat or oil when articles to be fried are placed therein, considerably more of the fat or oil must be in heated condition, and it is likewise important to have highly efficient means for supplying heat to the fat or oil as heat is used up in the frying operation.

It is usually the custom to keep enough heat input to keep the fat or oil at about the frying temperature and when frying begins to rapidly increase the heat input as by turning up the source of heat. The latter almost universally consists of gas or oil burners which deliver a relatively large volume of heated combustion gases to the tank by the expedient of having the gases traverse a series or multiple of fiues which pass through the tank or cooking vessel.

It is one of the primary objects of the present invention to provide more efficient heat-transfer means for deep fat fryers.

It is a further object of the present invention to provide baffles made of a highly heat-resistant material, positioned within the heating tubes through which the hot gases pass so that, as these baffles attain visible red heat, they will act as radiant elements to radiate heat to the walls of the heating tubes.

It is a further object to make these baffles in the form of a wire-mesh network, so that they may abstract heat from the heating gas most effectively.

The present invention is illustrated by two sheets of drawings, showing only such details as are required for a proper understanding of the principles of the invention. In these drawings:

Figure 1 is a perspective view of a heating tube containing the baffles above mentioned;

lg. 2 is a vertical section through the heating tube along line i.2 of Fig. l and shows a part of two of the vertical baffles;

Fig. 3 is an end view of the tube shown in Fig. 1;

Fig. 4 is a horizontal longitudinal section through the tube along line i-d of Fig. 1 and shows the elongated first bafiie in top plan view;

and

Fig. 5 is a vertical longitudinal section along the line '55 of Fig. l, and also indicates the burners used to supply hot combustion gases to the tube.

In order to obtain the maximum amount of heat from the flame and combustion gases of the burners, woven wire bafiies are placed in a heating tube which is placed similarly to the fire tubes of a steam boiler. The wire is preferably of an alloy which will withstand repeated heating to red heat without appreciable oxidation or weakening. Accordingly, so-called Nichrome wire was selected. This has been commercially available for many years and has the approximate composition of 60% nickel, 15% chromium, less than 0.1% carbon, less than 0.3% manganese, about 1.3% silicon, and the rest iron. It has been used primarily as for electrical heating elements. In the present instance, however, it is used both as a heat absorber as well as heat radiator. 7

Thus in the walls 6 of a suitable tank intended for the reception of cooking or frying fat or oil, there are placed tubes 1, one of which only is shown, but it is to be understood that there may be a plurality of them. This tube 3 is preferably made polygonal in cross section, and in the embodiment illustrated is hexagonal, with the two vertically extending opposed sides 8 and 9 being longer than any of the other four.

Extending into the tube for about one-half its extent is a horizontal dividing bafile i0 made of Nichrome wire-mesh. This is slightly wider than the inside diameter of the tube l and is bowed upwardly and sprung into the tube, thereby providing an upper l I as well as a lower passageway I2. As can be seen from Fig, 5, two burners l3 and I l serve to inject flames and the resultant products of combustion into the two respective spaces H and I2 and, as a result of the high temperature of these flames, the longitudinal bafiie Iii will become red hot and hence will strongly radiate heat to the six sides of the tube 1. These sides will thus be highly heated, and as the tubes are made of metal, such as stainless steel, Monel metal, etc, they will readily conduct heat to the fat or oil.

As the temperature of the gases drops, the heating effect becomes lessened. Therefore, the rest of the tube 1 is fitted with a number of vertically extending bent Nichrome wire mesh bat" fies l5, l6 and ll. As shown in Figs. 4 and 5, the bafiles may be three in number, and comprise attaching portions 58 which are in contact with the two lower sides l9 and 26 of the tube 1, and are preferably spot-welded thereto. The

baffles themselves consist of two halves 2! and The result will be a most eflicient utilization ;Which carry the radiated z-heat away. so-fast that burning of. the. fator oil is avoided, fresh oi-lcon- ,tinually coming contact with the-tubes to .ab- ,sorb, the available.-, :heatenergy. .:It was found that-round tubes heated-either by gas or :electricity were limitedras to theheatinput, interms of, B. t.- u. to arheatdischarge,notlgreater than the equivalent often :watts ,per square "inch of surface heating area-,- whilewith the construction of, the present invention a heat-dischargeas "great as 45 watts per squareinch; of heatingssurface is possible, Itisbelieved that the radiant heat discharge, is mainly, responsible" for this im- ,provement.

As Nichrome Wire resists destruction by heat for a long time,- the baflies will iastialmost indennitely, while if they wereimade-o f ordinary soft ironor steel, they would v,c uicklyssuccumb to the oxidation to. which-. theywould unavoidably be subjected, because the combination-gases while low in available :oxygen, nevertheless-drawinair by their aspiratingefiect.

1 The presentinventiomhas .been=:found. tobe very useful and efiective. -It will beviconsidered as within the scope of: the present invention to make the bafiles fromiother. than wire=mesh, suoh as expanded vNichrome. sheetswperforated or slitted N ichrome; sheets, orieven ,solid; sheets; .although thebetter. results are obtained from wire mesh-as illustrated.

' Applicant claims:

L- In heati .tubesadapted for heating liquids the combination of ahorizontally -.d isp.osed tube for traversal of: highly; heated -gases,.,andsheatradiating elements therein. comprising a horizontally disposed-:mediatemesh Work, and. a plurality of vertically-positioned. baffles, of.v mesh work, the saidmesh work beingmade of aniclrelchromium-iron alloy, said baflies being arranged in st gered relationship in said tube by being securedalternatelyto oppositesides jof th'e tube and extending, toward. the opposed .w'alll thereof.

2.,In' heating tubes. adaptedfor heating liquids the combination of a horizontally-disposed tube for traversal othighly-heated gases, and heatradiating elements .ther'ein comprising a. horizontally disposed mediate mesh work and a plurality, of vertically positioned b'afiies ;of mesh work,,said mesh Work being made 'of a.ni'ckelchromium-ironv alloy, said horizontally disposed ,meshi work extending, medially through about none-half ofi the lengthof' the tubeandthe bafiles being arranged in staggered relationship in the other half of said tube by being secured alternately to opposite sides ;of the tubeand' extending about to the center thereof. 7 V

3. In heating tubes adapted for heating liquids the combination of, a horizontally disposedftube for traversal of highly heated gases, and heatradiating elements therein comprising a horizontally disposed mediatemesh work and a-plurality of vertically positionedbafiles of mesh one-halfof'the 'lengthof the tube *and the baiiles being arranged in staggered relationship in the *other half of said tube by being secured alternat elytoopposite-sides of the tube and extending about to the center thereof, the horizontally dispos'ed mesh work being at the portion of the tubereceiving. the gases.

4. A heating tube for deep fat fryers and the likefcomprising a substantially hexagonal tube having two opposed sides longer than the other four, a. nickelechromiu-m-iron i alloy. mesh work extending longitudinally s for. about one-half, .the length of the tuberandpositioned.soas toextend across. saiditube, and. a .pluralityof transversely extending .nickelechromium-iron. alloy .7 .meshworkbaflies staggeredly positionedron. the other half .of said tube andrbenteback upon themselves at about a 30?..angle andisecured. alternately. to opposite sides. of said, tube andiextending toward the opposed wall thereof, saidnickelchroinium iron, alloyu-havingrhigh. heat emissivity whereby .heatabstracted. from hot gases traversing said .tubes will be radiatedtothe. sides thereofjthereby increasing the efficiency of the'heating tube. 5 A heating tube-for deep fat fryers comprising. a: horizontallyl disposed polygonal-tube .ar-

ranged for the passage ofv highly heated gases, and having an inlet and an outletend, a heatradiat'ing Nichrome wire-mesh horizontall'y'and longitudinally extending baffle. extending from the inlet endfor a portion into saidtube; thereby vdividing. it into an upper and. a lower passageway, and a plurality of vertically extending Nichrome wire-mesh bafiles-rin' the rest "of 'the tube,iarrangedsalternately on oneand theothe'r side Qfthemedianplaneof said tube.

6. .A heating tube for the transmissionof heat to ailiquid comprising a tube arranged for ithe passage therethroughbf highly heated gases, and having an inlet andan outlet end, a heat-radiating .foraminous longitudinal bafilei extending fromsthe inletend .for a portion. into lsaid' tube,

.therebydividing it into two parallel longitudinal passageways, and a pluralitylo'f transverse .foraminous bafiles inthe further portioniof said tube secured alternately to opposite sides f thereof and extending toward the opposite wall'to' that' to which theyare attached.

7.. A heating tube for the transmission "of. heat to a liquid comprising a tube arranged for the passage therethrough of highly heated gases, and having an inlet and an outlet end, a heat radiating wire-mesh longitudinalbaiile exten'dingirom 'theinlet endtfor a portion into'said'tube, thereby dividing it into two parallel longitudinalpassageways, and a plurality of transverse wire-mesh battles in the further portion of said tube'secured alternately to opposite sides thereof and extending substantially to the 'mecli'an longitudinal plane 'ofsaid tube.

- WILLIAM. C.'- PROEHL.

References Cited in the file of this patent UNITED" STATES PATENTS Number .Name i Date 2,400,653 ODowd May 21, 1946 2,424,612 GFunter serum-s- Ju-1y:129, 1 947 FOREIGN PATENTS Number Country Date 11,959 Great Britain June 19, 1895 

